1. Field of the Invention
The present invention relates to an apparatus for positioning a smoothing roll which is mounted so as to be displaceable by means of a cantilever arm against the reeling mandrel of a strip coiler and to be adjustable particularly with a roll changing head against the reeling mandrel with the use of force application means.
2. Description of the Related Art
When coiling thin strips, particularly aluminum strips, it is known in the art to place a smoothing roll during the entire coiling process against the reeling mandrel or on the strip coiler in order to prevent air inclusions and strip defects, so called couch defects.
Because of jumps of the roll due to a diameter increase at the strip beginning, the so-called layer jump, the roll rotates unsteadily and hammer-like vibrations of the entire roll arm occur. In the past, it was not possible to eliminate this disadvantageous phenomenon even by using springs and dampers.
DE 33 18 031 A1 discloses a method and an apparatus for controlling the pressure rollers of a strip coiler influenced by pressure medium-operated cylinders. In accordance with this known method, in which the pressure rollers serve to introduce and press the first and last strip layers against the reeling mandrel or the previously wound strip layers, the strip beginning of the entering strip is observed and monitored without contact during the formation of the first winding and its respective position is utilized for positioning the pressure rollers.
In the apparatus for carrying out this known method, optical sensors are provided for the contactless monitoring of the strip beginning and an optical sensor is arranged immediately following each pressure roller as seen in the travel direction. The method and the apparatus require complicated mechanical and control-technological elements, so that, particularly when a diameter change of each strip layer occurs in the area of the strip beginning, the generation of markings due to mass inertia of the pressure rollers on the strip surface are avoided. For this purpose, the pressure rollers are controlled in such a way that they are moved back each time by a distance corresponding to the strip thickness before the strip beginning which causes the diameter jump passes the rollers. The reeling mandrel is coupled to a pulse generator which interacts with a pulse counter which starts to operate after a contact of the strip beginning at the reeling mandrels without slip has been achieved. It has also been proposed to observe and monitor without contact the strip beginning of the entering strip when the first winding is formed and to utilize the respective position for positioning the pressure rollers.
EP 0 391 135 A2 discloses a method of reeling strip in reeling plants. Using the method for controlling the pressure roller adjustment of a strip coiler which has become known under the name step control, it is possible to coil even strips on the reeling mandrel without damage. For this purpose, it is proposed that the pressure rollers move the strip as closely as possible to the reeling mandrel without, however, applying pressure forces against the reeling mandrel, or that only the last pressure roller in the entry direction of the strip moves the strip against the reeling mandrel, while the remaining pressure rollers move the strip as closely as possible to the reeling mandrel without exerting any pressure forces against the strip or the reeling mandrel. The contact of the strip against the reeling mandrel without slip is achieved by a position-controlled spreading of the mandrel segments.